This invention relates to a process for restoring a damaged part of a battery of coke ovens such as a heating wall wherein masonry briding material is selected to provide a flat connecting surface and an expansion joint between the restored part of the masonary and the masonry briding material as well as the existing masonry to remain for continued use as part of the oven masonry. More particularly, the present invention relates to such a process for restoring a damaged part of a heating wall by an improved construction and an arrangement of brick-like or castable forms of bridging material to form a closure and support for existing masonry while at the same time providing low thermal expansion so as to compensate for thermal expansion of the renewed part of the heating wall and without developing undesirable forces on the existing masonry in the coke oven for continued use.
While not so limited, the present invention is primarily concerned with a process for the partial restoration of heating walls of a coke oven battery wherein a connecting surface is formed between the masonry to remain as part of the heating wall and the renewed portion of masonry for the heating wall. Such connecting surfaces are aligned to form a flat surface whereby under a load a lateral expansion joint is provided for the new construction of the heating wall between the flat surface and the replacement pieces of the heating wall. A horizontal expansion joint adjacent to the lateral expansion joint is incorporated between the new masonry and the continuous surface formed on the existing masonry.
The partial restoration of heating walls for coke oven batteries, especially such batteries having horizontal coking chambers, is a procedure designed to repair damage to brickwork arising from prolonged operation of the coke oven battery. To date, such damage could not be repaired and thus necessitated the shutting down of the coke oven battery for disassemblying and repairing the damaged portions thereof. Successful repairs of this type, on the other hand, will enable prolonged operation of the coke oven battery and thus maintain older coke oven batteries operational at a time when the need for coke is increasing. Moreover, this reduces the need for constructing new coke ovens to an absolute minimum.
As is known in the art, building bricks, having a relatively high expansion property, are used in coke oven construction for reasons of cost. The thermal expansion of common silicia brick is normally about 1.2% to 1.5% at operating temperatures prevailing in the coke ovens. The thermal expansion of the masonry is structurally compensated for and taken into account in various ways. The horizontal expansion is frequently accommodated by springs that are installed on the tie columns in the front of the heads of the heating walls. However, there are materials used to form building brick that exhibit little or no thermal expansion from ambient to normal operating temperatures of coke ovens. Nevertheless, these materials are generally too expensive for use to form conventional coke oven masonry.
Repair to the masonry of coke oven chambers having a relatively high thermal expansion property must, therefore, be carried out in such a way that the masonry remaining for continued use is maintained at a relatively high temperature of, for example, between 800.degree. C and 1000.degree. C, in order to avoid the contraction that would otherwise occur in the masonry upon substantial cooling. Moreover, substantial cooling of the masonry will, of itself, cause additional disintegration and destruction of the masonry. On the other hand, the replacement masonry used to form a restored part of the heating wall must be connected in a manner such that dimensional changes, particularly length changes that occur during subsequent heating, do not result in new damage. Expansion joints are generally provided to avoid such damage. These joints are formed, for example, from mortar that hardens only at the operating temperatures of the oven battery or from wooden inserts that burn out when the oven masonry is heated and thus provide the desired additional space to compensate for thermal expansion.
Finally, when undertaking repairs to a coke oven battery, one must take into consideration different types of damage which differ sharply from each other in their peculiarities. Damage to the heads of the coking chamber partition is, of course, the most frequent area of damage because the sharpest temperature drops and differences, e.g. stresses, during the coke pushing operation occurs at this site during the operation of the coking battery. However, sometimes the segment of the masonry between the heads is damaged. Should this occur, the entire chamber partition could then fall in on a segment between the oven heads. It is possible to detect damage at an early stage so that one wall of only one or more of the heating flues is damaged while the opposite wall of the heating chamber remains intact. Of course, it is then essential to remove, or break out, as little as possible of the undamaged masonry when undertaking repairwork.
In West German Patent Publication No. 2,122,729, there is disclosed a process for the partial restoration of heating walls for a horizontal oven chamber in a battery of coke ovens. This process permits the partial restoration of the entire chamber partition at the heads of the battery or on segments between the oven heads. In this process, after providing the necessary insulation for the working space and the subsequent dismantling of the damaged masonry, connector surfaces are prepared in the form of a continuous smooth surfaces. These surfaces are hewed out of the masonry which is still standing and part of the coke oven battery. Thus, the remaining masonry is used to form a lateral expansion joint while at the other side of the joint there is formed the segment of the masonry that is to be restored.
In this known restoration process, the hewing out of the connector surfaces to form a continuously smooth surface for an expansion joint is difficult work because it must be carried out on the remaining masonry at an elevated temperature. Consequently, there occurs new undesirable breakouts of the masonry and sharp cooling. This also produces cracks in the masonry and extensive leakage. In addition, it is not always possible to assure the stability of the remaining masonry at the site and thus, the replacement of masonry at the segment to be restored is sometimes inadequate.